Large‐Scale Modulation of Left‐Handed Passband in Hybrid Graphene/Dielectric Metasurface

Abstract

Large‐scale modulation of the left‐handed transmission with a high quality factor is greatly desired by high‐performance optical devices, but the requirements are hard to be satisfied simultaneously. This paper presents a hybrid graphene/dielectric metasurface to realize a large transmission modulation for the left‐handed passband at near‐infrared frequencies via tuning the Fermi energy of graphene. By splitting the nanoblocks, i.e. introducing an additional symmetry breaking in the unit cell, the metasurface demonstrates an ultrahigh quality factor (Q ≈ 550) of Fano resonance with near‐unity transmission and full 2π phase coverage due to the interference between Mie‐type magnetic and electric resonances, which induces the negative refraction property. Besides, the split in the nanoblock greatly enhances the local field by increasing the critical coupling area, so the light‐graphene interaction is promoted intensively. When the surface conductivity of graphene is electrically tuned, the hybrid graphene/dielectric metasurface exhibits a deep modulation of 85% for the left‐handed passband, which is robust even for the highest loss of graphene. Moreover, the simple configuration remarkably reduces the fabrication requirements to facilitate the widespread applications.